Question

可能重复：
JPA OneToOne and ManyToMany between two entities

我找到了无效的解决方案。我的问题是我有两个实体“员工”和“部门” 许多员工属于一个部门 One Department由One Employee领导。随时都会出现错误，同时引入@OneToOne和@OneToMany。这是代码

public class Department {
@Required
public String deptName; 

@OneToMany(mappedBy="dept")
public List<Employee> employees = new ArrayList<Employee>();

@OneToOne
public Employee deptHead = new Employee();

    .....   

}

public class Employee{
@Required
public String surname;

@Required
public String othernames;   

@OneToOne(mappedBy="depthead")
public Department headedBy = new Department();

@ManyToOne
public Department dept = new Department();

... 
}

是否可以同时使用aNnotation和工作？

Answer 1

应该是。

当您创建或要求JPA创建Employee的实例时，Employee会尝试实例化Department，实例化Employee。 ..，无限。

从类定义中删除= new Employee()和= new Department()表达式;使用适当的setter方法。
验证Department表上定义了一对一关系的SQL列是否已定义;具体而言，Department表具有引用Employee的外键。这样做的基础是@OneToOne(mappedBy="...")应该在JPA实体上定义不具有SQL外键，引用所做的实体。

除此之外，

@OneToOne(mappedBy="depthead")
public Department headedBy = new Department();

以及Department上的相应字段：

@OneToOne
public Employee deptHead = new Employee();

depthead和deptHead之间的情况不匹配。

JPA OneToOne和OneToMany在同一个实体上

1 个答案: